Samples of aluminum-alloy channels were tested for stiffness. the following frequency distribution was obtained. The distribution is assumed to be normal. stiffness frequency2480 232440 352400 402360 332320 21a) What is the approximate mean of the population from which the sample were taken?b) What is the approximate standard deviation of the population from which the samples were taken?c) What is the approximate probability that stiffness would be less than 2350 for any given channel section?

The answer is explained below

Step-by-step explanation:

stiffness        frequency

2480             23

2440             35

2400             40

2360             33

2320             21

a) The mean for the population is calculated using the formula:

b) The standard deviation is given by:

c) We have to find the z score for x = 2350. The z score is given by:

From the z table:

The probability that stiffness would be less than 2350 for any given channel section = P(x < 2350) = P(z < -1.02) = 0.1539 = 15.39%

the perimeter is increased by a factor of 2

10.416 meters per second

step-by-step explanation:

distance=1 00 meters

time= 9.6 seconds in decimal form or 9 3/5 as a mixed number

average speed= 100/9.6

=10.416 meters per second or 10 52/125 as a mixed number.